Fast moving, low flying, very large and long metallic object seen in daylight.

I saw a very large metal craft, cigar shaped, flying extremely low and fast going from North to South over 13 Mile Rd about a mile or two from where I was. I honestly thought it was a 747 making a crash landing on Woodward Ave, it was that big! This is in a highly populated area so surely someone else saw this thing. I thought it might possibly be a blimp, but after checking around the web, there are no events where you might find a blimp in this area. Also, I've never seen a blimp move at that rate of speed. This was at 7:15 PM, still very sunny outside at that time of day.